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13881. 题目: Estimating the soil respiration under different land uses using artificial neural network and linear regression models
文章编号: N18112901
期刊: CATENA
作者: Mitra Ebrahimi, Mohammad Reza Sarikhani, Ali Akbar Safari Sinegani, Abbas Ahmadi, Saskia Keesstra
更新时间: 2018-11-29
摘要: Soil respiration is a biological process in microbes that convert organic carbon to atmospheric CO2. This process is considered to be one of the largest global carbon fluxes and is affected by different physicochemical and biological properties of soil, land use, vegetation types and climate patterns. Soil respiration recently received much attention, and it could be measured in two states basal respiration (BR) and substrate induced respiration (SIR) which together gives a good representation of the general soil microbial activity. The aim of this study was to estimate the BR and SIR of 150 data points obtained from soil samples collected from the surface to 20 cm of depth under different land use categories using the Artificial Neural Network (ANN) and Linear Regression Methodology (LRM). This study is bringing data from an arid area, and there is little information on this issue. Soil samples were chosen from three provinces of Iran, with humid subtropical and semi-arid climate patterns. In each soil sample a variety of characteristics were measured: soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon (OC), OC fractionation data e.g. light fraction OC (LOC), heavy fraction OC (HOC), cold water extractable OC (COC) and warm water extractable OC (WOC), population of fungi, bacteria, actinomycete, BR and SIR. Our goal was to use the most efficient ANN-model to predict soil respiration with simple soil data and annual precipitation (AP) and mean annual temperature (MAT) and compare it with LRM. Our results indicated that for an ANN model containing all the measured soil parameters (14 variables), the R2 and RMSE values for BR prediction were 0.64 and 0.05 while these statistical indicators for SIR obtained 0.58 and 0.15, respectively; whereas the addition of AP and MAT data to this model (16 variables) caused a decrease in statistical indicators. When the R2 and RMSE values of the BR-ANN and SIR-ANN predicted using an ANN model with only 7 variables (including OC, pH, EC, CCE and soil texture) they were estimated to be 0.66, 0.043 and 0.52, 0.16, respectively. Overall, LRM in comparison to ANN had a lower R2. Therefore, the results show that ANN modeling is a reliable method for predicting soil respiration, even when based on easy to measure data. Our results revealed that highest and lowest BR and SIR were recorded in rice paddy soils and saline lands, respectively. In total, soil respiration (BR: 0.09 vs 0.06 and SIR: 0.46 vs 0.32 mg CO2 g−1 day−1) was higher in agricultural land compared to natural covered land.

13882. 题目: Climate-driven thresholds in reactive mineral retention of soil carbon at the global scale
文章编号: N18112821
期刊: Nature Climate Change
作者: Marc G. Kramer, Oliver A. Chadwick
更新时间: 2018-11-28
摘要: Soil organic matter can release carbon dioxide to the atmosphere as the climate warms. Organic matter sorbed to reactive (iron- and aluminium-bearing) soil minerals is an important mechanism for long-term carbon storage. However, the global distribution of mineral-stored carbon across climate zones and consequently its overall contribution to the global soil carbon pool is poorly known. We measured carbon held by reactive minerals across a broad range of climates. Carbon retained by reactive minerals was found to contribute between 3 and 72% of organic carbon found in mineral soil, depending on mean annual precipitation and potential evapotranspiration. Globally, we estimate ~600 Gt of soil carbon is retained by reactive minerals, with most occurring in wet forested biomes. For many biomes, the fraction of organic carbon retained by reactive minerals is responsive to slight shifts in effective moisture, suggesting high sensitivity to future changes in climate.

13883. 题目: Abiotic formation of condensed carbonaceous matter in the hydrating oceanic crust
文章编号: N18112820
期刊: Nature Communications
作者: Marie Catherine Sforna, Daniele Brunelli, Céline Pisapia, Valerio Pasini, Daniele Malferrari, Bénédicte Ménez
更新时间: 2018-11-28
摘要: Thermodynamic modeling has recently suggested that condensed carbonaceous matter should be the dominant product of abiotic organic synthesis during serpentinization, although it has not yet been described in natural serpentinites. Here we report evidence for three distinct types of abiotic condensed carbonaceous matter in paragenetic equilibrium with low-temperature mineralogical assemblages hosted by magma-impregnated, mantle-derived, serpentinites of the Ligurian Tethyan ophiolite. The first type coats hydroandraditic garnets in bastitized pyroxenes and bears mainly aliphatic chains. The second type forms small aggregates (~2 µm) associated with the alteration rims of spinel and plagioclase. The third type appears as large aggregates (~100–200 µm), bearing aromatic carbon and short aliphatic chains associated with saponite and hematite assemblage after plagioclase. These assemblages result from successive alteration at decreasing temperature and increasing oxygen fugacity. They affect a hybrid mafic-ultramafic paragenesis commonly occurring in the lower oceanic crust, pointing to ubiquity of the highlighted process during serpentinization

13884. 题目: Mercury Stable Isotope Fractionation during Abiotic Dark Oxidation in the Presence of Thiols and Natural Organic Matter
文章编号: N18112819
期刊: Environmental Science & Technology
作者: Wang Zheng, Jason D. Demers, Xia Lu, Bridget A. Bergquist, Ariel D. Anbar, Joel D. Blum, Baohua Gu
更新时间: 2018-11-28
摘要: Mercury (Hg) stable isotope fractionation has been widely used to trace Hg sources and transformations in the environment, although many important fractionation processes remain unknown. Here, we describe Hg isotope fractionation during the abiotic dark oxidation of dissolved elemental Hg(0) in the presence of thiol compounds and natural humic acid. We observe equilibrium mass-dependent fractionation (MDF) with enrichment of heavier isotopes in the oxidized Hg(II) and a small negative mass-independent fractionation (MIF) owing to nuclear volume effects. The measured enrichment factors for MDF and MIF (ε202Hg and E199Hg) ranged from 1.10‰ to 1.56‰ and from −0.16‰ to −0.18‰, respectively, and agreed well with theoretically predicted values for equilibrium fractionation between Hg(0) and thiol-bound Hg(II). We suggest that the observed equilibrium fractionation was likely controlled by isotope exchange between Hg(0) and Hg(II) following the production of the Hg(II)–thiol complex. However, significantly attenuated isotope fractionation was observed during the initial stage of Hg(0) oxidation by humic acid and attributed to the kinetic isotope effect (KIE). This research provides additional experimental constraints on interpreting Hg isotope signatures with important implications for the use of Hg isotope fractionation as a tracer of the Hg biogeochemical cycle.
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13885. 题目: Mechanisms of Interaction between Persulfate and Soil Constituents: Activation, Free Radical Formation, Conversion, and Identification
文章编号: N18112818
期刊: Environmental Science & Technology
作者: Guodong Fang, Xiru Chen, Wenhui Wu, Cun Liu, Dionysios D. Dionysiou, Tingting Fan, Yujun Wang, Changyin Zhu, Dongmei Zhou
更新时间: 2018-11-28
摘要: Persulfate-based in situ chemical oxidation (ISCO) for soil remediation has received great attention in recent years. However, the mechanisms of interaction between persulfate (PS) and soil constituents are not fully understood. In this study, PS decomposition, activation, free radical formation and conversion processes in 10 different soils were examined. The results showed that soil organic matter (SOM) was the dominant factor affecting PS decomposition in soil, but Fe/Mn-oxides were mainly responsible for PS decomposition when SOM was removed. Electron paramagnetic resonance (EPR) spectroscopy analysis showed that sulfate radicals (SO4•–) and hydroxyl radicals (•OH) generated from PS decomposition subsequently react with SOM to produce alkyl-like radicals (R), and this process is dependent on SOM content. R and SO4•–/•OH radicals predominated in soil with high and low SOM, respectively, and all three radicals coexist in soil with medium SOM. Chemical probe analysis further identified the types of radicals, and R can reductively degrade hexachloroethane in high SOM soil, while SO4•– and •OH oxidatively degrade phenol in low SOM soil. These findings provide valuable information for PS-ISCO, and new insight into the role of SOM in the remediation of contaminated soil.
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13886. 题目: Determination and Prediction of Zinc Speciation in Estuaries
文章编号: N18112817
期刊: Environmental Science & Technology
作者: Holly B. C. Pearson, Sean D. W. Comber, Charlotte B Braungardt, Paul Worsfold, Anthony Stockdale, Stephen Lofts
更新时间: 2018-11-28
摘要: Lowering of the estuarine Environmental Quality Standard for zinc in the UK to 121 nM reflects rising concern regarding zinc in ecosystems and is driving the need to better understand its fate and behavior and to develop and parametrize speciation models to predict the metal species present. For the first time, an extensive data set has been gathered for the speciation of zinc within an estuarine system with supporting physicochemical characterization, in particular dissolved organic carbon. WHAM/Model VII and Visual MINTEQ speciation models were used to simulate zinc speciation, using a combination of measured complexation variables and available defaults. Data for the five estuarine transects from freshwater to seawater endmembers showed very variable patterns of zinc speciation depending on river flows, seasons, and potential variations in metal and ligand inputs from in situ and ex situ sources. There were no clear relationships between free zinc ion concentration [Zn2+] and measured variables such as DOC concentration, humic and biological indices. Simulations of [Zn2+] carried out with both models at high salinities or by inputting site specific complexation capacities were successful, but overestimated [Zn2+] in low salinity waters, probably owing to an underestimation of the complexation strength of the ligands present. Uncertainties in predicted [Zn2+] are consistently smaller than standard deviations of the measured values, suggesting that the accuracy of the measurements is more critical than model uncertainty in evaluating the predictions.
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13887. 题目: Thermal conversion of a promising phytoremediation plant (Symphytum officinale L.) into biochar: dynamic of potentially toxic elements and environmental acceptability assessment of the biochar
文章编号: N18112816
期刊: Bioresource Technology
作者: Juan Du, Lei Zhang, Tao Liu, Ran Xiao, Ronghua Li, Di Guo, Ling Qiu, Xuanmin Yang, Zengqiang Zhang
更新时间: 2018-11-28
摘要: Symphytum officinale L., as a hyperaccumulator, was pyrolyzed into biochar at 350, 550, and 750 °C, respectively. PTEs could be enriched in biochars except Cd volatilized greatly at 750 °C. In order to evaluate the environmental acceptability of biochars, a series of sequential and single extractions and biochar oxidation procedures were performed for simulating different environmental conditions. There was a sharp decline in PTEs release under various conditions when the temperature above 550 °C, indicating PTEs might transform into more stable forms at higher temperature. Thus, increasing the pyrolysis temperature is helpful for reducing biochar phytotoxicity, suppressing biochar leaching and improving biochar environmental safety. Moreover, the economic feasibility analysis of the biochar confirmed the practicability of it. Findings from this work illustrated that biochars pyrolyzed from Symphytum officinale L. at the temperature higher than 550 °C might be environmental acceptable, which is beneficial for biochar application.
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13888. 题目: Effects of biomass pyrolysis derived wood vinegar (WVG) on extracellular polymeric substances and performances of activated sludge
文章编号: N18112815
期刊: Bioresource Technology
作者: Fang Zhang, Haiping Yang, Dabin Guo, Shihong Zhang, Hanping Chen, Jing'ai Shao
更新时间: 2018-11-28
摘要: The effects of wood vinegar (WVG) on extracellular polymeric substances (EPS), and flocculation, sedimentation and dewatering performances of activated sludge were investigated in sequencing batch reactor (SBR) process. Results showed that polysaccharide (PS) and DNA were accounted for the largest and smallest proportion of EPS, respectively. With WVG injection, productions of soluble EPS (S-EPS), loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS), protein (PN), PS, and DNA were significantly increased. The optimal WVG concentration was found as 4μl/l. The effects of WVG on different types of EPS followed an order of LB-EPS>TB-EPS>S-EPS. According to batch and long-term SBR operations, WVG could increase the biomass amount of activated sludge, which was beneficial to improve sewage treatment efficiencies. However, WVG showed negative impact on flocculation, sedimentation, and dewatering performance of activated sludge.

13889. 题目: Polyethyleneimine and carbon disulfide co-modified alkaline lignin for removal of Pb2 +  ions from water
文章编号: N18112814
期刊: Chemical Engineering Journal
作者: Qiaorui Wang, Chunli Zheng, Zhenxing Shen, Qiang Lu, Chi He, Tian C. Zhang, Jianhui Liu
更新时间: 2018-11-28
摘要: This paper reports the efficient removal of Pb2 + ions from water by modified alkaline lignin (MAL), in which alkaline lignin was used as the raw material and ornamented with amine/imine (–NH2/–NH) and dithiocarbamate (–CSS) groups by using polyethyleneimine (PEI) and carbon disulfide (CS2) as the modifier. The pseudo-second-order model and Langmuir model expressed the adsorption kinetics and isotherm well, indicating the adsorption of Pb2 + ions on MAL was a chemisorption and monolayer. The maximum adsorption amount (qm) of MAL towards Pb2 + ions was 79.9 mg/g, significantly higher than that of other reported biomass-based-sorbents such as Hamimelon peels (7.9 mg/g), dairy manure-derived biochar (37.8 mg/g), and acid-treated avocado kernel seeds (21.8 mg/g). Even after six continuous adsorption–desorption cycles, the values of qm for the regenerated MAL at each cycle were still obviously higher than those aforementioned sorbents. The binding affinity of different groups of MAL towards Pb2 + ions followed the sequence: C–N > –NH2 > N–H/O–H > C–S > CS. This work not only gave a comprehensive picture of the adsorption/desorption mechanism of Pb2 + ions on MAL but also evaluated the reusing ability of MAL. These results may provide insights for the further studies on the subsequent construction of devices to be used in bench- and pilot-scale experiments.
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13890. 题目: High efficient removal of bisphenol A in a peroxymonosulfate/iron functionalized biochar system: Mechanistic elucidation and quantification of the contributors
文章编号: N18112813
期刊: Chemical Engineering Journal
作者: Shun-Feng Jiang, Li-Li Ling, Wen-Jing Chen, Wu-Jun Liu, De-Chang Li, Hong Jiang
更新时间: 2018-11-28
摘要: Activation of peroxymonosulfate (PMS) to degrade recalcitrant organic pollutants has attracted much attention, however, this process usually needs expensive or toxic catalysts. Herein, we prepared a Fe functionalized biochar composite that contain Fe0, porous carbon with abundant functional groups and nanofibers (Fe-BC-700) to activate PMS and efficiently remove bisphenol A (BPA). The contribution of different participants in the complicated system involving Fe species, carbon composites, and radicals and nonradicals were quantitatively investigated. Under optimal conditions (0.2 g/L PMS and 0.15 g/L catalyst), 20 mg/L of BPA can be completely removed in 5 min by Fe-BC-700. The effects including the activation of PMS by Fe species to produce sulfate radicals (SO4), the electron transfer by the nanofiber-mesoporous carbon structure, and the inherent persistent free radicals (PFR) in biochar, were demonstrated to contribute to the high performance. A series of contrast experiments showed that PMS activated by Fe contributed to about 36% of BPA degradation, while the carbon composites, especially carbon nanofibers contributed to 17%, and the other 47% was ascribed to the adsorption of carbon composites (may further undergoing degradation). Meanwhile, the degradation by SO4 accounted for about 23% (by quenching experiments), while the nonradical pathway contributed to 30%. This work suggests that the non-activation factors in PMS/porous catalyst/pollutant system cannot be neglected.
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13891. 题目: Enhancement of dewaterability and heavy metals solubilization of waste activated sludge conditioned by natural vanadium-titanium magnetite-activated peroxymonosulfate oxidation with rice husk
文章编号: N18112812
期刊: Chemical Engineering Journal
作者: Changgeng Liu
更新时间: 2018-11-28
摘要: In this work, natural vanadium-titanium magnetite-activated peroxymonosulfate (VTM-PMS) oxidation coupled with rice husk (RH) as skeleton builder (VTM-PMS-RH) was employed to enhance sludge dewaterability for the first time. The optimal dosages of PMS, VTM, and RH were 200 mg/g total suspended solids (TSS), 1 g/g TSS, and 200 mg/g TSS, respectively. Under optimal conditions, capillary suction time (CST) reduction and water content of sludge cake (WC) were 82.1% and 72.9% after VTM-PMS conditioning, respectively, which further reached the values of 94.8% and 63.4% when coupled with RH treatment. Cycle experiments demonstrated that VTM reusability in VTM-PMS system for dewatering sludge was desirable. Based on sludge physicochemical properties after conditioning (i.e., extracellular polymeric substances (EPS), zeta potential, dissolved organic carbon (DOC), total nitrogen (TN), and volatile suspended solids (VSS) reduction), VTM-PMS oxidation shows the merits of EPS degradation, sludge disintegration, and charge neutralization. In addition, the transformation behaviors of heavy metals (HMs) in sludge after conditioning were investigated according to total HMs contents, speciation distribution, and leaching tests. Through conditioning, total HMs contents (Cu, Zn, Cr, and Pb) in liquid phase increased while were adverse in solid phase. The leaching toxicity reductions were 78%, 83%, 60%, and 100% for Cu, Zn, Cr, and Pb, respectively, obtained by VTM-PMS-RH conditioning. Meanwhile, the chemical speciation distribution of HMs in sludge was changed and transformed into more stable forms, as well as the environmental risk of HMs decreased. These results suggest that VTM-PMS-RH process has a synergistic contribution to the environmental risk reduction of HMs and their immobilization enhancement. Therefore, VTM-PMS-RH process is a promising alternative for sludge conditioning in terms of the enhancement of dewaterability and HMs solubilization.
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13892. 题目: Advanced treatment of bio-treated dyeing and finishing wastewater using ozone-biological activated carbon: A study on the synergistic effects
文章编号: N18112811
期刊: Chemical Engineering Journal
作者: Wen-Long Wang, Yi-Zhong Cai, Hong-Ying Hu, Jian Chen, Jing Wang, Gang Xue, Qian-Yuan Wu
更新时间: 2018-11-28
摘要: The advanced treatment of bio-treated dyeing and finishing wastewater (BDFW) in textile industries is urgently necessitated to reduce the discharge of pollutants from industrial wastewater and enhance wastewater reclamation. In this study, it was found that ozonation and biological activated carbon (O3-BAC) can synergistically degrade the dissolved organic carbon (43.0%), chemical oxygen demand (45.8%), color (73.0%), and specific UV absorbance (SUVA254) (29.7%) of BDFW. BAC alone could hardly degrade the fluorophore, but ozonation can transfer hydrophobic or hydrophilic protein-like fluorophore to less fluorescent transformation products that were more susceptible to biological degradation by BAC treatment. In comparison to BAC alone, O3-BAC, on one way, promoted the mineralization (27.0%–36.3%) of DOC and the degradation of chromophores (43.8%–48.0%) with low MW (<1 kDa); on another way, inhibited the formation of high MW fraction (>3 kDa) that was formed by BAC. Ozonation of BDFW resulted in a larger decrease of SUVA254 than electron donating capacity (EDC), while the BAC treatment of BDFW and ozonated BDFW induced contrasting results. This was likely due to the different degradation patterns that O3 decomposed DOM dominantly via the O3-addtion reactions, while biological process would simultaneously reduce low MW fractions with relatively higher EDC and form high MW fractions with lower EDC and more aromaticity.

13893. 题目: Removal of pharmaceuticals, toxicity and natural fluorescence through the ozonation of biologically-treated hospital wastewater, with further polishing via a suspended biofilm
文章编号: N18112810
期刊: Chemical Engineering Journal
作者: Kai Tang, Aikaterini Spiliotopoulou, Ravi K. Chhetri, Gordon T.H. Ooi, Kamilla M.S. Kaarsholm, Kim Sundmark, Bianca Florian, Caroline Kragelund, Kai Bester, Henrik R. Andersen
更新时间: 2018-11-28
摘要: In the present study, a pilot-scale ozonation system was introduced as post treatment to reduce the pharmaceuticals and toxicity in the effluent of a pilot-scale Moving Bed Biofilm Reactor (MBBR) treating hospital wastewater. The ozonated effluent was polished further by suspended biofilm carriers to remove biodegradable organic matter and toxicity generated from ozonation by-products. A laboratory ozonation system was used to mimic the experiments, which were carried out at the pilot plant so that the removal of pharmaceuticals in the pilot and laboratory experiments could be compared. Delivered ozone dose achieved 90% removal of pharmaceutical was obtained and it was normalised to dissolved organic carbon (DOC). These normalised results show that trimethoprim was eliminated by ozone easier than other pharmaceuticals.Fluorescence was found to be highly correlated to the removal of pharmaceuticals, and fluorescence with a wavelength of 275 nm of excitation and 310 nm of emission had the closest correlation. After polishing MBBR was introduced into the ozonated wastewater, half of its protein-like fluorophore was removed.The toxicity of the hospital wastewater during MBBR treatment was measured by Vibrio fischeri, the inhibition of which decreased from 80% to 50%. By applying ozonation, this inhibition reduced to 20%.
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13894. 题目: Rational design and synthesis of hollow Co3O4@Fe2O3 core-shell nanostructure for the catalytic degradation of norfloxacin by coupling with peroxymonosulfate
文章编号: N18112809
期刊: Chemical Engineering Journal
作者: Liwei Chen, Xu Zuo, Shengjiong Yang, Tianming Cai, Dahu Ding
更新时间: 2018-11-28
摘要: Rational design and synthesis of efficient catalyst for the generation of sulfate radicals (SO4) through heterogeneous approach is highly desirable. In the present study, a magnetic cobalt-based catalyst, Co3O4@Fe2O3 was successfully synthesized by using metal-organic frameworks (MOFs) as a template. A hollow core-shell structure possessing moderate specific surface area (22.8 m2 g−1) and pore volume (0.18 cm3 g−1) was obtained. The catalyst performed high efficiency for the degradation of norfloxacin (NOR) by coupling with peroxymonosulfate (PMS). And the process was kinetically favorable in neutral (0.43 min−1 at pH of 7.5) and weak acidic/basic conditions, whilst significantly inhibited at acidic condition (0.12 min−1 at pH of 4.5). Catalyst loading showed a more remarkable effect on the degradation process than PMS dose. Interestingly, chloride, phosphate and bicarbonate ions clearly promoted the degradation process while humic acid showed a detrimental effect. Cl2/HOCl oxidation system was demonstrated when massive Cl was added into the reaction system. As evidenced by electron paramagnetic resonance (EPR) analysis, both hydroxyl and sulfate radicals contributed to the degradation and the latter one played a crucial role. Eventually, degradation pathway was tentatively proposed based on the HPLC-ESI-MS/MS analysis of the detected intermediates. This study would be very meaningful to promote the applications of sulfate radical based advanced oxidation processes (SR-AOPs) for the environmental remediation.
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13895. 题目: Records of Carbon and Sulfur Cycling During the Silurian Ireviken Event in Gotland, Sweden
文章编号: N18112808
期刊: Geochimica et Cosmochimica Acta
作者: Catherine V. Rose, Woodward W. Fischer, Seth Finnegan, David A. Fike
更新时间: 2018-11-28
摘要: Early Silurian (∼431 Ma) carbonate rocks record a ca. 4.5‰ positive excursion in the stable isotopic composition of carbonate carbon (δ13Ccarb). Associated with this isotopic shift is a macroevolutionary turnover pulse known as the ‘Ireviken Event’. The onset of this carbon isotope excursion is commonly associated with a shallowing-upward facies transition that may have been accompanied by climatic change, as indicated by a parallel positive shift (∼0.6‰) in the stable isotopic composition of carbonate oxygen (δ18Ocarb). However, the relationships among carbon cycle perturbations, faunal turnover, and environmental changes remain enigmatic. Here we present a suite of new isotopic data across the Ireviken Event from multiple sections in Gotland, Sweden. These samples preserve no systematic change in δ18Ocarb but show positive excursions of equal magnitude in both carbonate (δ13Ccarb) and organic (δ13Corg) carbon. In addition, the data reveal a synchronous perturbation in sulfur isotope ratios, manifest as a ca. 7‰ positive excursion in carbonate-associated sulfate (δ34SCAS) and a ca. 30‰ positive excursion in pyrite (δ34Spyr). The increase in δ34Spyr values is accompanied by a substantial, concomitant increase in stratigraphic variability of δ34Spyr.The relatively constant offset between the δ13Ccarb and δ13Corg excursions throughout the Ireviken Event could be attributed to increased organic carbon burial, or possibly a change in the isotopic composition of CO2 sources from weathering. However, a positive correlation between carbonate abundance and δ13Ccarb suggests that local to regional changes in dissolved inorganic carbon (DIC) during the shallowing-upward sequence may have been at least partly responsible for the observed excursion. The positive excursion recorded in δ34SCAS suggests a perturbation of sufficient magnitude and duration to have impacted the marine sulfate reservoir. An inverse correlation between CAS abundance and δ34SCAS supports the notion of decreased sulfate concentrations, at least locally, consistent with a concomitant increase in pyrite burial. A decrease in the offset between δ34SCAS and δ34Spyr values during the Ireviken Event suggests a substantial reduction in the isotopic fractionations (εpyr) expressed during microbial sulfur cycling and pyrite precipitation through this interval. Decreased εpyr and the concomitant increase in stratigraphic variation in δ34Spyr are typical of isotope systematics observed in modern shallow-water environments, associated with increased closed-system behavior and/or oxidative sedimentary reworking during early sediment diagenesis. While the isotopic trends associated with the Ireviken Event have been observed in multiple locations around the globe, many sections display different magnitudes of isotopic change, and moreover, are typically associated with local facies changes. Due to the stratigraphic coherence of the carbon and sulfur isotopic and abundance records across the Ireviken Event, and their relationship to changes in local depositional environment, we surmise that these patterns more closely reflect biogeochemical processes related to deposition and lithification of sediment than global changes in carbon and sulfur burial fluxes.

13896. 题目: Surface nano-engineered wheat straw for portable and adjustable water purification
文章编号: N18112807
期刊: Science of The Total Environment
作者: Ting Li, Fang Fang, Yu Yang, Wanji Shen, Weiwei Bao, Tianran Zhang, Fanrong Ai, Xingwei Ding, Hongbo Xin, Xiaolei Wang
更新时间: 2018-11-28
摘要: Wheat straw (WS), as a cheap and abundant agricultural waste, is usually burned directly in farmland and causes severe air pollution. Therefore, biochar derived from waste WS is prepared and modified by nanoscaled zinc oxide through a facile in-situ surface-modification process. For ease of use, a 3D printed finger-sized unit (FSU) loaded with the above as-prepared WS is designed and implemented. Each unit weighs only 4 g, and could simultaneously reduce three major water contaminants: bacteria, organic dyes, and heavy metal ions. Moreover, it is interesting to note that fresh wheat straw is a flexible material and has excellent electrical conductivity after carbonization. These two properties (flexibility and conductivity) could further adjust water purification performance. The subsequent cellular and animal tests confirmed the biosafety of the water purified with FSU alone.
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13897. 题目: Tracking the historical sewage input in South American subtropical estuarine systems based on faecal sterols and bulk organic matter stable isotopes (δ13C and δ15N)
文章编号: N18112806
期刊: Science of The Total Environment
作者: Ana Caroline Cabral, Marines Maria Wilhelm, Rubens C.L. Figueira, César C. Martins
更新时间: 2018-11-28
摘要: Faecal sterols and stable isotopes (δ13C and δ15N) from bulk organic matter (OM) were analysed in three sedimentary cores collected in two subtropical bays located in the South Atlantic to evaluate historical trends in the sewage input and to track possible changes in the bulk isotopic composition of OM in recent decades. The values of δ13C and δ15N ranged from −27.4 to −25.0‰ and from 0.5 to 3.9‰, respectively, without a clear trend in the variation over the whole period covered by sediment cores and with no conclusive interpretation of a specific range value typically related to the sewage input for these areas. The maximum coprostanol concentration was 0.19 μg g−1 in the upper 4 cm of one core, which was not considered contaminated by evaluation of the sterols diagnostic ratios. Even at low levels, the coprostanol concentrations followed variations in urban and economical regional development. Baseline values for faecal sterols (in average between 0.03 and 0.05 μg g−1), which may represent a previous non-impacted environment scenarios, were calculated for use in comparative perspectives for future evaluations of the sewage input and contamination.
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13898. 题目: An effective method for reconstructing the historical change in anthropogenic contribution to sedimentary organic matters in rivers
文章编号: N18112805
期刊: Science of The Total Environment
作者: Shanshan Wang, Guijian Liu, Jiamei Zhang, Li Zhou, Paul K.S. Lam
更新时间: 2018-11-28
摘要: Surface water quality has been greatly affected by anthropogenic activities around the world in the past decades. Scientists and policymakers should pay close attention to quantify historical change in human impacts on aquatic environment. An effective method for reconstructing the historical input of anthropogenic organic matters in aquatic environment is urgently required. Here, five sediment cores from the Huaihe River were analyzed for n-alkanes (C8–C40) and isoprenoid alkanes (pristane and phytane) using gas chromatography–mass spectrometry (GC–MS). Sixty years (1955–2014) sedimentary history of n-alkanes was reconstructed using 210Pb method. The evaluation of wax n-alkanes percentage (WNA) indicated that the terrestrial higher plant input was predominant in most samples. The main anthropogenic sources were the petroleum hydrocarbon, fossil fuel combustion and the discharge of industrial wastewater and domestic sewage. The results of principal component analysis-multiple linear regression (PCA-MLR) indicated that the respective contributions of anthropogenic and biogenic sources to sedimentary organic matters were 47.8% and 48.1% in the Huaihe River. Furthermore, the anthropogenic contribution displayed a decrease trend from 1991 to 2014, which probably attributed to the effective pollution control measures taken by the local government. However, the anthropogenic contribution was still considerable during this period. Thus, the government should pay attention to organic pollution control in the Huaihe River sediments continuously. In summary, this study provides an effective method for reconstructing the historical change in anthropogenic contribution to sedimentary organic matters in rivers, which can probably be applied to other aquatic environment around the world.
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13899. 题目: Influence of pyrolysis temperature and feedstock on carbon fractions of biochar produced from pyrolysis of rice straw, pine wood, pig manure and sewage sludge
文章编号: N18112804
期刊: Chemosphere
作者: Siye Wei, Mengbo Zhu, Xingjun Fan, Jianzhong Song, Ping'an Peng, Kaiming Li, Wanglu Jia, Haiyan Song
更新时间: 2018-11-28
摘要: In this study, the influences of feedstock and pyrolysis temperature on carbon fractions of biochar were investigated. Four types of organic wastes (rice straw (RS), pine wood (PW), pig manure (PM) and sewage sludge (SS)) were pyrolyzed at different temperatures (300 °C, 400 °C, 500 °C, 600 °C and 700 °C). Biochar produced at low temperature exhibited high yields, high dissolved organic carbon (DOC) content and unstable organic carbon content. In contrast, biochar formed at high temperature showed high C content and C stability with a low O/C and H/C ratios. In addition, the biochar pyrolyzed from PW contained the lowest DOC of the four biochar types. The properties of DOC fractions (F1, F2 and F3) released from biochar differed depending on feedstock, pyrolysis temperatures, and extraction procedures. The highest specific ultraviolet absorbance at 254 nm of the F1 and F2 fractions were observed for RS biochar, suggesting that more aromatic organic matter was present in sequentially extracted fractions of RS biochar than in extracts from the other biochars. In addition, the hot water extracts (F2) mostly showed higher aromaticity than cold water extracts (F1). The stability of biochars was greatly enhanced at pyrolysis temperatures >500 °C. If the biochars produced in this study were to be used for carbon sequestration in soil, the first priority should be PW, followed in order by RS and PM.

13900. 题目: Adsorption behaviour and mechanisms of cadmium and nickel on rice straw biochars in single- and binary-metal systems
文章编号: N18112803
期刊: Chemosphere
作者: Yiyi Deng, Shuang Huang, David A. Laird, Xiugui Wang, Zhuowen Meng
更新时间: 2018-11-28
摘要: Adsorption mechanisms and competition between Cd2+ and Ni2+ for adsorption by rice straw biochars prepared at 400 °C (RB400) and 700 °C (RB700) were investigated in this study. Based on the Langmuir model, the maximum adsorption capacities (mg g−1) of Cd2+ and Ni2+ on RB400 and RB700 were in the order of Cd2+ (37.24 and 65.40) > Ni2+ (27.31 and 54.60) in the single-metal adsorption isotherms and Ni2+ (25.20 and 32.28) > Cd2+ (24.22 and 26.78) in the binary-metal adsorption isotherms. Cd2+ competed with Ni2+ for binding sites at initial metal concentrations >10 mg L−1 for RB400 and > 20 mg L−1 for RB700. The adsorption sites for Cd2+ and Ni2+ on the biochars largely overlapped, and the binding of Cd2+ and Ni2+ to these sites was affected by the occupation sequence of these metals. For Cd2+ and Ni2+ adsorption in the binary system, cation exchange and precipitation were the dominant adsorption mechanisms on RB400 and RB700, respectively, accounting for approximately 36% and 60% of the adsorption capacity. Competition decreased the contribution of cation exchange but increased that of precipitation and other potential mechanisms. Results from this study suggest that types and concentrations of metal ions should be taken into account when removing metal contaminants from water or soil using biochars.
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